I tweaked this a bit to work better in my environment, not too loud, not too hot. It's still quiet enough to not bother me.

The average CPU temperature is down 14 degrees when the fan is set ~600 RPM higher (running at 1500-1800 RPM, previously never going above 1250. I've NEVER seen the fan above 1600 RPM without modifications, it's insane and it's bad for the hard drives.).

CPU temperature is now 48 degrees (was 62) and hard drives are down ~6 degrees (were 47-51, now 41-42).

This is for RN204 and 6.4.2, but I think it's usable with other units - just find the three correct paths for your model in the beginning of /root/fanoverride.

The fan temperature was somehow set to some insane negative value, and the NOTHING should be multiplied by 100.
I added a timestamp to the log because I run locate32 every hour which indexes the drive and really stresses the NAS, that's the way I came up with the values that I use in the script - by checking how hot it got, how fast the fan spun, and when the drives were being used or not.

Also I corrected the spelling error just because it bothered me.

Sorry for my bad English, I'm really tired.

This code was originally written by dishmagic66, modified by m1byo, and now modified slightly by me. All credits go to them.

If you don't have nano, get it. Instructions are somewhere in this thread.

The code for

/root/fanoverride

#!/bin/bash

## Variables ##
FANPWMPATH=/sys/devices/platform/soc/fd880000.i2c-pld/i2c-0/0-003e/hwmon/hwmon0/fan1_target
FANSPEEDPATH=/sys/devices/platform/soc/fd880000.i2c-pld/i2c-0/0-003e/hwmon/hwmon0/fan1_input
CORETEMPPATH=/sys/devices/virtual/thermal/thermal_zone0/temp

MAXFAN=3500   # Maximum operable speed
MINFAN=600     # Minimum operable speed

MINTEMP=35
MAXTEMP=75
NEWSPEED=1000  # Initial fan speed (%)

## Functions ##
function getReadings {
        FANPWM=$(cat $FANPWMPATH)
        FANSPEED=$(cat $FANSPEEDPATH)
        CORETEMP=$(cat $CORETEMPPATH)
        }

function setFanSpeed {

        TEMPFAN=$(expr $MAXFAN - $MINFAN)
        NEWFAN=$(expr $TEMPFAN \* $NEWSPEED)
        NEWFAN=$(expr $NEWFAN / 100)
        NEWFAN=$(expr $NEWFAN + $MINFAN)
        if [ $NEWFAN -lt $MINFAN ]; then
                NEWFAN=$MINFAN
                fi
        if [ $NEWFAN -gt $MAXFAN ]; then
                NEWFAN=$MAXFAN
                fi

        echo New Speed: $NEWFAN RPM

        echo $NEWFAN > $FANPWMPATH
        }

function calcFanPercent {
        TEMPRAN=$(expr $MAXTEMP - $MINTEMP)
        TEMPREL=$(expr $CORETEMP - $MINTEMP)
        TEMPREL=$(expr $TEMPREL \* 100)
        TEMPPER=$(expr $TEMPREL / $TEMPRAN)
        NEWSPEED=$TEMPPER
        echo New Speed Set: $NEWSPEED % at $(date +%T)
        }


###################################################################
echo "Automatically controlling fan speed..."
while true
        do
                getReadings
                echo "Temp: $CORETEMP C FAN: $NEWSPEED% [$FANSPEED RPM] [PWM $FANPWM]"

                calcFanPercent
                setFanSpeed

                sleep 5
        done
###################################################################

Then just

chmod 755 /root/fanoverride

(The plus thingy that someone wrote about doesn't work)

Create /etc/init.d/fanoverride with this content:

#!/bin/sh
### BEGIN INIT INFO
# Provides: FanOverride
# Required-Start: $local_fs $network $named $time $syslog
# Required-Stop: $local_fs $network $named $time $syslog
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Description: FanOverride overrides the default ReadyNAS fan control
### END INIT INFO

SCRIPT=~/fanoverride
RUNAS=root

PIDFILE=/var/run/fanoverride.pid
LOGFILE=/var/log/fanoverride.log

start() {
if [ -f /var/run/$PIDNAME ] && kill -0 $(cat /var/run/$PIDNAME); then
echo 'Service already running' >&2
return 1
fi
echo 'Starting service.' >&2
local CMD="$SCRIPT &> \"$LOGFILE\" & echo \$!"
su -c "$CMD" $RUNAS > "$PIDFILE"
echo 'Service started' >&2
}

stop() {
if [ ! -f "$PIDFILE" ] || ! kill -0 $(cat "$PIDFILE"); then
echo 'Service not running' >&2
return 1
fi
echo 'Stopping service.' >&2
kill -15 $(cat "$PIDFILE") && rm -f "$PIDFILE"
echo 'Service stopped' >&2
}

uninstall() {
echo -n "Are you really sure you want to uninstall this service? That cannot be undone. [yes|No] "
local SURE
read SURE
if [ "$SURE" = "yes" ]; then
stop
rm -f "$PIDFILE"
echo "Notice: log file is not be removed: '$LOGFILE'" >&2
update-rc.d -f <NAME> remove
rm -fv "$0"
fi
}

case "$1" in
start)
start
;;
stop)
stop
;;
uninstall)
uninstall
;;
retart)
stop
start
;;
*)
echo "Usage: $0 {start|stop|restart|uninstall}"
esac

I don't think I modified that at all. The only thing that doesn't work is that the script doesn't tell you if the service is already started. That's another reason why I added the timestamp, if you're unsure if the service is started just

less /var/log/fanoverride.log

and check the timestamp.

Anyway, then you run

chmod 755 /etc/init.d/fanoverride
update-rc.d fanoverride defaults

Then you either restart or

service fanoverride start

And thats it! (At least that's what I did).

You might have to fix leafp2p as well if you get an error about that, there's instructions for that in https://community.netgear.com/t5/Using-your-ReadyNAS/LSB-issue-on-leafp2p/td-p/929396

Now; can someone please tell me how the unit originally adjust the fan speeds, and how to control the LCD? ;)

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